I have a 2000 Isuzu Trooper with the 40L30E automatic transmission. The transmission shudders when throttle is applied at about 35 mph. The transmission was recently completely rebuilt approximately 5,000 miles ago and now the problem is back. The torque converter was also replaced with rebuilt unit.
Then you need to go back to whomever dealt with the transmission. This is probably torque converter clutch shudder and, if it is, the it would indicate that something wasn’t done quite right in the rebuild. It could be something else - but your first stop has to be with the transmission rebuilder.
Sadly enough, the trooper is at the transmission shop that rebuilt it and has been there for three weeks. The rebuild came with a one year/10,000 mile warranty. They claim to have gone completely through it again, changing the torque converter and planetary gears again. Now they are stumped and there my trooper sits.
Your best bet is to have transman come by. I am not even a mechanic. But I’ve managed to learn a few things over the years.
First, you’re probably going to need a new shop. But you need to collect all of the very specific details on what they have done for diagnosis. They must have scanned for error codes, for instance. Find out and find out what the codes are. Find out - in specific terms - what else they have done for diagnosis. Also find out what kind of rebuild they did - soft parts only? (this would be bad and unlikely, but it is done).
Get all of the details you can and post them. Even down to the brand and part number of the transmission fluid they installed. (Some of this info may be on an invoice - e.g. posting a parts list from the initial rebuild would be good).
Another thing is that not all presumed transmission problems originate in the transmission. Sometimes the transmission is fine and just doing what it is told by the engine computer. But the engine computer is giving wacky instructions b/c there is a problem elsewhere. Do you happen to know, for instance, whether or not the throttle position sensor has been checked? How about the MAF/MAP sensor? (I don’t know what this car has - some have one or the other, some have both). In addition, there are the electrical transmission controls - some of those might be acting up and, if reused, have been the problem all along. You need an expert trans tech with the right kind of scanning equipment.
Just how certain is anyone that this problem is transmission related and that it’s not an engine performance problem?